Electrosurgery is commonly used to cauterize, cut and/or coagulate tissue. In typical electrosurgical devices, RF electrical energy is applied to the tissue being treated. Local heating of the tissue occurs, and, depending upon the waveform of the applied energy and the electrode geometry, the desired effect is achieved. By varying the power output and the type of electrical waveform, it is possible to control the extent of heating and, thus, the resulting surgical effect. For example, a continuous sinusoidal waveform is best suited for cutting, while a waveform having periodically spaced bursts of a partially rectified signal produces coagulation.
In bipolar electrosurgery, the electrosurgical device includes two electrodes. The tissue being treated is placed between the electrodes, and the electrical energy is applied across the electrodes. In monopolar electrosurgery, the electrical excitation energy is applied to a single electrode at the surgical site, and a grounding pad is placed in contact with the patient. The energy passes from the single monopolar electrode through the tissue to the grounding pad.
Bipolar electrosurgical devices are generally known to be safer than monopolar electrosurgical devices because the area of tissue through which electrical current passes is confined to the area close to the two electrodes of the bipolar device. However, bipolar devices include several drawbacks. For example, bipolar devices tend to char tissue during use and develops an open circuit relatively quickly because the electrical energy delivered by the devices is concentrated at the tissue located between the two electrodes. Bipolar devices also tend to adhere or stick to tissue during use. Any sticking of tissue to one or both electrodes short circuits the electrical energy and reduces the effectiveness of the device on the desired target tissues. To minimize tissue sticking, power settings on a bipolar generator are typically decreased compared to the settings on monopolar generator outputs. While this reduces charring and sticking, it also slows the intended effect of cauterization and makes the cutting of tissue with bipolar energy impractically slow, thereby slowing the progress of a surgery. For this reason, bipolar instruments have not been readily accepted by general surgeons in spite of their safety advantages.
Improving the effectiveness of bipolar electrosurgical devices includes eliminating the sticking of target tissues to the electrodes and reducing the formation of char material. Such improvements reduce short circuiting of the electrodes during operation and allow the electrodes to be passed from one target to another without the need for cleaning. The use of devices having heat pipes that conduct heat from the electrode and a surgical site to a heat exchanger, such as are disclosed in U.S. Pat. No. 6,074,389, herein incorporated by reference in its entirety, can be used to overcome these shortcomings. Such electrosurgical devices permit the user to increase the power levels of an attached electrosurgical generator during a surgical procedure. This speeds the action of the instruments compared to other currently available bipolar instruments.